The zona pellucida is a glycocalyx that surrounds maturing cocytes. It is actively synthesized during oogenesis until just prior to ovulation. A method has been devised for large scale isolation of the zona and subsequent purification of its three component glycoproteins. Particulate zonae were used to immunize male rats. The resulting polyclonal antibodies specifically immunoprecipitated all three of the 125I-zona proteins and bound to the zona of oocytes and early embryos as demonstrated by indirect immunofluorescence labelling utilizing a fluorescein conjugated sheep anti-rat Ig antibody. Spleen cells from the same rats were fused with murine SP2/0 myeloma cells and resulting hybridomas were selected in HAT media. Several clones secreted monoclonal antibodies which are specific for the zona pellucida glycoproteins. These specific immunological probes are being used to study the supramolecular structure of the zona pellucida during development. They also will be used to immunoprecipitate in vitro translation products to determine the availability of zona specific mRNA's during development.